Method of inputting starting and destination points into navigation systems

ABSTRACT

A method inputting starting and destination points into an electronic navigation system for motor vehicles in which relevant data of street system maps comprising a street identification character and reference point coordinates with assigned house numbers, are stored in a data storage. When inputting, the street identification character and house number of the starting and destination point are entered, then the data storage is first searched for the street identification character and then for the inputted house number. When there is agreement with a house number of the reference points in the data storage its coordinates are taken over for navigation. When there is a disagreement, the reference points adjacent to it in the data storage are determined and the coordinates of the starting or destination point are determined by means of interpolation and used for navigation (FIG. 20).

BACKGROUND OF THE INVENTION

The invention relates to a process for inputting starting anddestination points into electronic navigation systems of vehicles.

In a navigation system designated TRAVELPILOT, it is known, according tothe brochure BP-VFW/8699901010 of Blaupunkt-Werke GmbH, to show therespective road map with the instantaneous location of the vehicle on amonitor during navigation driving. In this system, the street name or aprominent location, such as a railroad station or airport, is inputtedvia keys prior to navigation driving. These given destinations containedin the data storage of the navigation system are then marked in thestreet map on the monitor. During navigation driving, the respectivelocation of the vehicle on the street map is plotted by compoundnavigation. The respective remaining straight-line distance from thedestination is superimposed on the monitor as additional data.

This system has the disadvantage that the data storage of the navigationsystem is not extensive enough to receive all of the street map datarequired for navigation. Thus, it is not possible to input apredetermined house from the houses on a street as a starting ordestination address, since only a limited number of prominent buildingsor building complexes are stored in the data storage of the street mapas possible destination points. Therefore, with this navigation system,the driver of the vehicle is, in most cases, only guided to the streetinputted as destination, so that he must still search for thedestination point on the street, i.e. a building with a determined housenumber.

In another process for inputting and storing locations and destinationsin a navigation data storage known from WO 86/01442, the polarcoordinates of the starting and destination points are determined with aspecial measuring instrument from desired maps and inputted into thecorresponding storage of the navigation computer together with the scaleof the map via keys and displays. During navigation driving (driving ofthe vehicle under the control of the navigation system), the directionand distance of the selected destination point are then displayed by thecompound navigation or in other words with the determination of theinstantaneous position of the vehicle on the street map during thedrive. This solution has the disadvantage that great care must be takenwhen determining and inputting the starting and destination points bytheir polar coordinates. Moreover, since the respective exact address,i.e. street and house number, can sometimes not be learned from the citymaps or can only be estimated when inputting destinations, suchdestinations can neither be exactly inputted nor accurately approachedby compound navigation.

SUMMARY OF THE INVENTION

The object of the invention is a method of inputting calling street andhouse numbers of the starting and destination points in navigationsystems for vehicles in which street reference points of street systemmaps provided with house numbers are stored in a data storage.

According to the method invention, relevant reference points of streetsof a street system map which are provided with house numbers, areavailable in the data storage with data protection from data of theheterogeneous data bases. The reference points are utilized wheninputting starting and destination addresses for determining thestarting and destination point of a navigation drive in the mostaccurate manner possible. An advantage of this process consists in thatthe storage capacity for the data storage of the navigation system canbe considerably reduced by storing individual reference points of thestreet as compared to the storage of all the buildings of the streetwith their house numbers. Accordingly, it is possible to storeelectronically entire city maps of large cities in the navigationsystem.

The present invention both to its construction so to its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following detailed description of specificembodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a flow chart of a method for obtaining the relevant data ofa series of streets;

FIG. 2 shows a flow chart for calling intermediate storage of the dataof a street;

FIG. 3 shows the mapping of a street with focal-point houses asreference points of the street;

FIG. 4 shows a flow chart for averaging closely adjacent referencepoints of the street;

FIG. 5 shows the reference points of the street from FIG. 3 with acircumscribing rectangle, divided into subrectangles;

FIG. 6 shows a reduced number of reference points of the street fromFIG. 3 with enlarged subrectangles;

FIG. 7 shows the reference points of the street, according to FIG. 3,remaining after averaging twice;

FIG. 8 shows a flow chart for the linearization of the street map;

FIGS. 9 to 15 show the view of the street reference points withindividual portions of the linearization;

FIG. 16 shows the street mapping by means of a traverse (a connectingline between various points) after linearization;

FIG. 17 shows a flow chart for smoothing or flattening the streetmapping;

FIG. 18 shows the block wiring diagram of a navigation system in themotor vehicle;

FIGS. 19 and 20 show flow charts for start and destination input intothe navigation system.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates a flow chart which shows the method steps forattaining the relevant data for a street from a data base of a surveyingoffice containing the focal-point coordinates of the houses on theselected street. It is assumed that a data base is necessary fornavigating according to city map data; the simplest possible outline ofthe city map should be contained in the data base. The data must be in aform which is understandable for the navigation system and easy tomanage. Information is required for each individual street, the courseof the street, its geographical situation, and data on the distributionof the house numbers along the street follow from this information insuitable form.

The information about the house numbers on the street should allowconclusions to be drawn concerning the situation of a predeterminednumber on the street. For short streets or squares, the house number haslittle significance in principle, since in this case the only concern isto find the street or square at all. But the house number has greaterimportance when it is desirable to drive to a predetermined point instreets covering a large surface area. Since almost all German surveyingoffices possess collections of data concerning the focal points ofproperty and houses for the areas under their jurisdiction, thesecollections of data are particularly suitable for obtaining relevantdata of street system mapping for navigation purposes. The processsections, which are shown in FIG. 1 and described in more detail below,are run one after the other in an electronic data processing system foreach street in the street system mapping.

After the start 10, in a first process section 11 for a selected street,the focal points of the houses located on this street are called fromthe heterogeneous data pool and stored temporarily. In process section12, closely situated house focal points are averaged to a form a commonfocal point, so that a portion of the original data is dispensed with.In process section 13, the entire series of streets is linearized intoone or more straight partial distances until all the houses within apredetermined band width lie next to the linearized course of the seriesof streets. The starting and ending points of the straight partialdistances are stored temporarily and the remaining intermediate pointsare dispensed with. In process section 14, two consecutive linearizedpartial distances are smoothed to form a common new partial distanceonly when this new partial distance lying between the two end points oftwo adjacent previous partial distances does not exceed a predetermineddistance from the common point lying in between. In this case, the pointlocated between these two consecutive partial distances is alsocanceled. In process section 15, the remaining reference points withtheir coordinates and the house numbers assigned to them are stored inthe data storage of the navigation device along with the identificationcharacter of the street. In step 16, the program is stopped. The sameprocess is repeated for every other street of the street system mapuntil all of the streets are included and the data relating to theirmapping are stored in the data storage.

The individual process sections from FIG. 1 are explained in more detailwith the aid of the following figures from a data collection with thefocal-point coordinates of houses. FIG. 2 shows a flow chart for callingthe house focal-point coordinates, their conversion into ascendingsequence of house numbers and their intermediate storage. A street isfirst selected from the street system map to be stored from theheterogeneous data base after the start 10. This street is now providedwith an identification character, e.g. a four-digit number, which issubsequently registered in a street index of the street system map forstart and destination input during navigation drives. The identificationcharacter, which increases with every newly called street, is now storedtemporarily in step 18 for the selected street. In step 19, the data ofthe houses of this street are then called from the data base one afterthe other by ascending house numbers. Three data blocks are storedintermediately for every house, wherein the first block contains athree-digit house number. The second block contains the x coordinate ofthe house focal point and the third block contains the y coordinate.Since the coordinate values are in the form e.g. of Gauss-Krugercoordinates in a rectangular coordinate system with the equator asreference axis in a known manner and require a very great storage space,these coordinates are converted in step 20 into a coordinate system witha reference point within the street system map, e.g. the lower left-handcorner of the street system map. The focal point coordinates of thehouses which are converted in this way now require substantially lessstorage space. The conversion is particularly simple to carry out if thenew reference point is likewise to be taken from the data material withits Gauss-Kruger coordinates. In this case, the difference between the xand y coordinates of the house focal points forms the new referencepoint. The data of all houses of the called street which are obtained inthis way are now stored temporarily with the house numbers as so-calledreference points of the street in step 21.

In FIG. 3, the course of a street 23 with blind alleys branching offfrom it, is shown in a defined region of the street system map to bestored. Moreover,, all reference points 24 stored there temporarily inthe process section according to FIG. 2 are shown with their housenumbers. From them the data relating to the street system mapping are tobe obtained with the process according to FIG. 1. Caution must beexercised so that no additional data concerning the street is availableother than the quantity of the reference points 24 with theircoordinates. The actual street course which is plotted is not to begathered form the heterogeneous data collection. At most it can beestimated from the situation of the house focal points and thedistribution of the house numbers.

FIG. 4 shows a flow chart with which the quantity of reference pointsfor the street is reduced by averaging the focal points of closelyadjacent houses. After the start 25 of this program section 12 from FIG.1, those reference points 24 of the street which lie furthest away arefirst determined and stored temporarily in step 26. A rectangle in whichthe x and y coordinates of these reference points are combined to formthe corner point coordinates of the rectangle is then formed with thesereference points in step 27. In FIG. 5 this rectangle, which comprisesall reference points 24 of the street, is designated by 36. Therectangle 36 determined by the temporarily stored corner points is nowdivided up into a plurality of subrectangles 37 in step 28 according toFIG. 4. The number of subrectangles 37 is determined by the number ofreference points 24 per street. It has proven advisable for the numberof subrectangles 37 per rectangle to divide the number of referencepoints 24 by the number 4 and to round off the results.

FIG. 5 shows this subdivision for the street according to FIG. 3. Inthis example, there is a subdivision of the rectangle 36 into 8×8subrectangles 37 with a total of 33 reference points of the street.These subrectangles 37 are also first stored temporarily with theircorner point coordinates. However, such a subdivision is only to becarried out in streets having a minimum quantity of houses, e.g. atleast 14 houses. Therefore, in step 29 of the flow chart from FIG. 4, acheck is made as to whether or not the rectangle 36 was divided intomore than nine subrectangles 37 in the preceding step 28. Since this isthe case in the present example, all subrectangles 37 are checked oneafter the other in step 30 as to whether or not two or more referencepoints 24 lie in one or more of the subrectangles 37. If this is thecase, the coordinates of the respective reference points 24 of such asubrectangle are averaged in step 30 and a focal point is formed fromthis, one of the house numbers of the averaged reference points 24 beingassigned to this focal point, and this house number is then storedtemporarily with the coordinates of the focal point. The previousreference points in this subrectangle can now be canceled. In so doing,it may possibly be advisable to assign to the focal point the housenumber of the reference point 24 lying closest to the focal point.

In the example according to FIG. 5, five focal points 38 were formed bymeans of averaging and were stored in step 30 in five of thesubrectangles 37, so that six reference points 24 can be canceled. Instep 31, the number of subrectangles per side of the rectangle is nowhalved, i.e. the surface area of the subrectangles is increased by amultiple of four. FIG. 6 shows that the rectangle 36 has now beendivided into 4×4 subrectangles 37a. In step 32 of the flow chartaccording to FIG. 4, another check is made as to whether or not thequantity of the subrectangles 37a formed in this way exceeds the numberof nine subrectangles. Since this is the case in the example, allenlarged subrectangles 37a are now checked one after the other in step33 as to whether or not more than two reference points 24 lie in one ormore of the subrectangles 37a. In so doing, the outer reference pointsdetermined in step 26 are not taken into account. In step 33, anaveraging of the coordinates of all reference points 24 included by asubrectangle 37a is now affected again. Eight additional focal points 38are formed by means of this averaging according to FIG. 6, the lowesthouse number of the combined reference points of the respectivesubrectangle 37a being assigned to these focal points 38 in the example.These focal points 38 are stored temporarily as new reference pointswith the house numbers and coordinates assigned to them, and theprevious reference points 17 of the respective subrectangles 37a can becanceled. FIG. 7 shows the relatively uniform new reference pointdistribution after averaging twice. The remaining original referencepoints 24 and the focal points obtained by means of averaging are nowstored together in a data storage as reference points of the street withtheir coordinates, the house numbers assigned to them, and the streetidentification character in step 34; specifically, together with thefour outer reference points of the street obtained in step 26, whichouter reference points are not taken into consideration in thedetermination in steps 30 and 33. In this way, data relating to thestreet is obtained from a heterogeneous collection of data with thehouse focal points of a street while taking into consideration dataprotection regulations, and accurate navigation driving (driving of thevehicle under the control of the navigation system) is enabled with thisdata by means of inputting a starting and destination address withdesignation of the street identification character and house number in asystem with a compound navigation. The storage requirement in the datastorage of the navigation system is considerably reduced compared to thestorage requirement in the heterogeneous collection of data.

In determining reference points according to the process sectionaccording to FIG. 4, it is important that the quantity of subrectanglesbe made dependent on the quantity of reference points 24 of the streetin the first subdivision of the rectangle 36 comprising all referencepoints. When the houses are distributed along the street in a relativelyuniform manner it is possible that no subrectangle 37 containing morethan one reference point 24 will be found in step 30. In this case, theenlargement of the subrectangles 37 according to step 31 is carried outimmediately. These process steps are consequently repeated until a focalpoint formation is carried out or until the number of subrectangles hasbeen reduced to nine. If this is already the case in step 29, noaveraging is carried out. The program then jumps immediately to step 34.

In order to find the beginning and end of the street, the referencepoints 24 with the highest and lowest house numbers are also stored inthe data storage in step 34 of the flow chart in FIG. 4 as fixedreference points of the street with their coordinates for furtherprocessing or as relevant data of the street. In the example, the numberof reference points 24 is reduced from 33 to 17 by averaging.

In a modification of the flow chart, according to FIG. 4, it may beadvisable in steps 26-34 first to call only the reference points witheven house numbers, store them temporarily, combine them insubrectangles possibly to form focal points, and store them with thehouse numbers assigned to them. The same process steps ar then carriedout with the reference points of the street having an uneven number. Ofcourse, the process steps can also be carried out in the reverse orderwith the uneven house numbers first and then with the even housenumbers. The number of reference points of a street is decisive for theformation of the subrectangles 37, 37a. The number of reference points24 should be divided by a whole number multiple of 1 for the number ofsubrectangles 37 to be formed per side of the rectangle 36 comprisingthe reference points 24. When there is a smaller number of referencepoints, it would have to be divided by 2 or 3. When there is a verylarge number of house reference points, it is advantageous to repeat theenlargement of the subrectangles 37 and the averaging and temporarystorage, according to steps 30 and 33 from the flow chart according toFIG. 4, repeatedly until 3×3 subrectangles are obtained for everystreet.

If there are relatively few house focal points as reference points in astreet, it is advantageous to select a large enough number ofsubrectangles per rectangle side when forming the subrectangles 37 sothat there is no more than one reference point in any of thesubrectangles. The subrectangles can then be increased until tworeference points occur in one of the rectangles, a new focal point cannow be formed from the two reference points by means of taking theaverage. After this first focal point formation, the subrectangles arenow increased again until there are two reference points in anothersubrectangle. These reference points are now also combined by averagingto form another focal point and are stored temporarily in case theminimum number of nine subrectangles is not yet reached. The enlargementof the subrectangles can be repeated many times. However, the averagingand focal point formation should be limited to a maximum of two passesso that no excessive distortion of the reference points occurs.

Another reduction of the reference points of a street is achieved bymeans of a linearization of the series of streets which is carried outin section 13 of the flow chart according to FIG. 1. This processsection follows the process for averaging and focal point formationaccording to FIG. 4. During the linearization, the reference points ofthe street achieved in the preceding process section are to be furtherreduced. In so doing, the existing reference points are first visualizedas connected with one another in ascending or descending sequence of thehouse numbers assigned to them by means of a traverse which is thenreplaced by a simpler one. This simpler traverse is then examined as towhether or not it describes the predetermined traverse of the existingreference points with sufficient accuracy. If this is the case, thesimple traverse, i.e. the reference points connected by it, is useddirectly and the remaining reference points are removed from the screen.If, on the other hand, reference points lie too far next to thissimplified traverse, the latter is expanded and compared again with thereference points.

In a flow chart, FIG. 8 shows the process section for the linearizationof the street mapping on the basis of the reference points 24 of thestreet 23 from FIG. 3 achieved in FIG. 7. After the start 40, thereference point having the lowest house number is first called in step41 from the existing reference points 24 of the street and stored asstarting point. In step 42, a check is made as to whether or not thereis a plurality of reference points for the called street. If this is notthe case, then the called street must be a square or a very short streetwhich is only characterized by one house. This reference point is thenstored in the data storage as the only reference point of the street andthe program jumps back to the main program in step 43. If there is aplurality of reference points 24--as in the present case--the referencepoint with the largest house number is called in step 44 and storedtemporarily as end point. The rest of the process section is nowexplained with the aid of FIG. 9. In the latter, the starting point hashouse number 3 and the end point is house number 35. In step 45, astraight line A is made through the starting and end points inmathematical form. In the next step 46, the reference point with thenext highest house number proceeding from the starting point is calledand the vertical distance of this starting point from the straight lineA is measured and stored temporarily in step 47. In step 48 a check ismade as to whether or not the end point of the straight line A isreached. As long as this is not the case the reference point with thenext highest house number is called in a loop in step 46 and itsdistance from the straight line A is measured again in step 47 andstored temporarily. Finally, if the end point on this straight line isreached, the reference point with the greatest temporarily storeddistance from the straight line A is called in step 49; in the examplethis is the reference point with house number 15, whose perpendicularline relative to the straight line is shown in a dash-dot line. Thisdistance b is now compared in step 50 with a predetermined limitingvalue of which forms a tolerance area to the left and right of thestraight line A. This limiting value is given at 40 m in the example. Ifall reference points lie within the area described by this limitingvalue a to the left and right of the straight line A, the course of thestreet is assumed to be sufficiently linearized by this straight line A.A check is made in step 51 as to whether or not the present end pointhas the highest house number. If this is the case, the starting pointand end point are given out as remaining reference points of the streetin step 52 and all remaining reference points are canceled in step 53.The program now jumps back into the main program according to FIG. 1 instep 54.

However, in the example according to FIG. 9, the distance b of thereference point with house number 15 is greater than the predeterminedlimiting value a. The previously used end point, i.e. the referencepoint with house number 35, is now given in a stack in step 55 and theobtained reference point with house number 15 is included as a new endpoint in step 56, and program steps 45-50 are run through again via aloop 57, wherein the straight line B is formed in step 45 and thereference point with house number 8 is found in step 49 as the one withthe greatest distance from the straight line B. In step 50 it isdetermined again that this reference point with house number 8 has adistance which is greater than the limiting value a. The previous endpoint with house number 15 is therefore placed in the stack in step 55and the reference point with house number 8 is included in step 56 asthe new end point. The program can now be run through again via the loop57.

FIG. 10 shows that a reference point with house number 7 is found againby means of this new loop running of the program according to FIG. 8with the straight line C, the distance of the reference point from thestraight line C being greater than the predetermined limiting value a.The program section via the loop 57 must therefore be run through again,wherein the straight line D is now formed. The distance of the referencepoint with house number 4 now exceeds the limiting distance a again, sothat the straight line E is now formed via the loop 57 of the flowchart.

FIG. 11 shows that the remaining reference point with house number 3anow has a distance from the straight line E which does not exceed thepredetermined limiting value a. In step 51 of the flow chart accordingto FIG. 8, a check is made as to whether or not the end point with housenumber 4 found in this way is simultaneously the highest house number ofthe street. Since this is not the case in the example, the end pointfound in this way is stored in step 58 and this found end point is nowset as new starting point in step 59. The last end point stacked in step55 is now removed from the stack as new end point in step 60 and theprevious process steps 45-60 are run through again via the loop 61. Inthe example, the point with house number 7 is found as new end point instep 60 and the straight line F is accordingly formed in step 45according to FIG. 11. In this case, also, the intermediate referencepoints are within the limiting value, so that the end point with housenumber 7 is stored in step 58 and is the new starting point in step 59.The reference point with house number 8 is called from the stack in step60 as new end point and the straight line G is accordingly formed. Inthe same way, the straight line H is subsequently found. The referencepoint with house number 11a also does not lie outside the limitingvalue, so that the reference points with house numbers 8 and 15 arefinally also stored in step 58.

As shown in FIG. 12, the point with house number 35 is now removed fromthe stack as new end point in step 60 of the flow chart according toFIG. 8, and steps 45-60 are now run through via the loop 61 again in thedescribed manner until the reference point with the highest house numberis recognized as end point in step 51. With respect to FIG. 12, thismeans that the reference point with house number 29a is first found asnew end point with the straight line I and that the straight line J isthen formed between the new starting point and end point.

FIG. 13 shows that a new end point with house number 20 is found againwith the aid of the straight line J and the straight line K isaccordingly formed. The reference point with the house number 17 is nowfound by means of the straight line K and the straight line L isaccordingly formed. Since no further reference points lie between thestarting point and end point of the straight line L, the reference pointwith house number 17 is now stored in step 58 of the flow chartaccording to FIG. 8.

FIG. 14 shows that the straight line M is now placed between thereference point with house number 17 and the new end point with housenumber 29 which is removed from the stack and that no further referencepoints lie between the starting point and end point of this straightline M, so that the end point with house number 20 is now stored in step58 and the straight line N is formed with the new end point with housenumber 29a which is removed from the stack.

It can be seen from FIG. 15 that the reference point with house number21 lying outside the limiting value a is found as new end point via thestraight line N, which new end point now forms the straight line O withthe starting point. Since no further reference points lie between thestarting point and end point of the straight line O, the end point withhouse number 21 is consequently also stored in step 58 and subsequentlyforms the straight line P with the new end point 29a. Since thereference point with house number 21a lies at a distance from thestraight line P within the limiting value a, the end point with housenumber 29a is now also stored in step 58. The reference point with housenumber 35 is now removed from the stack as new end point in step 60 andthe straight line Q is accordingly formed. Since the intermediatereference points in this instance also do not exceed the limiting valuea, this end point is finally recognized in step 51 as reference pointwith the highest house number. The original starting point with thelowest house number as well as all end points stored in step 58 are nowtransferred to a data storage in step 52 and all remaining referencepoints are canceled in step 53.

FIG. 16 shows a traverse formed in this manner between the remainingreference points, which traverse comprises partial distances or sectionsof the straight lines E, F, G, H, L, K, O, P, Q. The course of thestreet 23 to be mapped is shown in approximate form by means of thistraverse. A jumping back into the main program according to FIG. 1 istherefore affected in step 54 of the flow chart according to FIG. 8.

By this process, a linear street course is first assumed from the focalpoint of the house with the lowest house number and that with thehighest house number and a check is made as to whether or not thisstreet course describes the positions of all house focal points withsufficient accuracy. If all the points lie within the area described bythe predetermined limiting value to the left or right of the formedstraight lines, the course of the street is determined with sufficientaccuracy by means of this straight line. However, if reference pointsare found, as in the example, which have a greater vertical distancethan the predetermined limiting value, the previous straight line mustbe further improved by means of a traverse. For this purpose, the foundreference point which is at the furthest distance from the new traverseis accepted and the process is repeated with the partial distances orstraight lines which are accordingly formed. In so doing, only thosereference points are considered whose house numbers lie between therespective starting and end points of the partial distances or straightlines. FIGS. 9 to 15 show the respective successively formed straightlines by means of solid lines, lines with widely spaced dashes and linesclosely spaced dashes.

The final traverse shown in FIG. 16 has only 10 reference pointscompared to FIG. 9 with 17 reference points. It is also possible tocarry out a reduction of the reference point data from the data from theheterogeneous collection of data for every street without averaging orfocal point formation, respectively, in process section 12 of the mainprogram according to FIG. 1 by skipping over the averaging processaccording to the flow chart from FIG. 4. In the same way, the startingand end points are then determined with the flow chart according to FIG.8 by means of the data of the reference points with the highest andlowest house numbers of the street by storing them in the data storageand then forming an intermediate straight line. The coordinates of thetemporarily stored reference points of the street are then called oneafter the other and the distance of the reference points from thestraight lines is determined. The greatest distance found is comparedwith a predetermined limiting value. In the event that the greatestreference point distance is less than the limiting value, only the dataof the reference points with the highest and lowest house numbers andthe street identification character are stored in the data storage. Onthe other hand, all remaining reference point data of the street aresuppressed. In the event that the greatest reference point distance isgreater than the limiting value, this reference point is temporarilystored as new end point with its house number and a new first straightline is formed between it and the reference point with the lowest housenumber. A new second straight line is formed between it and thereference point with the previously highest house number. These processsteps are now repeated for every new straight line until all referencepoint distances are less than the predetermined limiting value. Thedistances of the reference points from the respective straight lines areprogressively determined proceeding from one end of the street or from astarting or end point, respectively.

In a modification of the process flow according to FIG. 8, alinearization of the street to be mapped can also be realized with theaid of the existing reference points in that the distances of thereference points from the straight lines are progressively determinedproceeding from the starting point, temporarily stored and compared withthe respective previous reference point distance until the distance ofthe current reference point is reduced relative to the previousreference point. The temporarily stored greatest reference pointdistance is then compared with the predetermined limiting value. In theevent that the reference point distance is smaller than thepredetermined limiting value, the reference point distances continue tobe progressively determined and compared with one another. The greatestreference point distance determined is then compared with thepredetermined limiting value again. As soon as a reference pointdistance is found which is greater than the predetermined limitingvalue, it is stored temporarily as new end point. The process steps arenow repeated until all reference points lying between the starting pointand the new end point are at a distance from the straight line which iswithin the predetermined limiting value. The obtained end point is nowstored as a new starting point and all intermediate reference points arecanceled. A new straight line is now formed between the new startingpoint and the end point of the street and the distances of theintermediate reference points from the new straight line are againcompared with one another and with the predetermined limiting value inthe manner described above. In this way, the course of a street ismapped in that the reference points which are finally stored in thestorage are tracked through a traverse with linear portions at apredetermined limiting value of e.g. 50 m until the deviation of thedetermined reference points from the actual course of the street hardlyexceeds the limiting value.

The process section described with the flow chart according to FIG. 8for the linearization of the course of the street can likewise becarried out separately by means of reference points with even housenumbers and reference points with odd house numbers. During navigationdriving, houses can accordingly be found on a street with sharplydivergent building density in an improved manner.

After running through the linearization in section 13 of the mainprogram according to FIG. 1, a smoothing of the traverse obtained forthe street mapping, shown in FIG. 16, is carried out in section 14. Thisprocess section is explained in more detail with a flow chart in FIG.17. After the start 62, a check is first made in step 63 as to whetheror not there are more than two reference points for the street mapping.If this is not the case, a linearization can not be carried out, sinceit is assumed in this case that the street runs linearly between the tworeference points which mark the beginning and end of the street.Therefore, a jumping back into the main program according to FIG. 1 isaffected in step 64. However, if three or more reference points areprovided for the street mapping, the reference point with the lowesthouse number is called first in step 65 and stored as starting point instep 66. On the street map according to FIG. 16, this corresponds to thereference point with house number 3. In step 67, the reference pointwith the next highest house number, house number 4 in this example, iscalled and temporarily stored. In step 68, the next highest referencepoint after the latter, house number 7 in this example, is called andtemporarily stored as end point. In step 69, a straight line is placedmathematically between the starting point and the end point and in step70 the distance of the intermediate reference point from the straightline is measured. In step 71, this distance is compared with a limitwhich is given as 10 m in the example. If the determined distance of themean reference point is not greater than the limit, a smoothing isaffected between the starting point and end point of the straight linesin that the mean reference point is now canceled in step 72 and the endpoint is used in step 73 as new starting point. However, if thedetermined distance of the mean reference point--as in the exampleaccording to FIG. 16--is greater than the predetermined limit, the meanreference point is stored temporarily in step 74 as new starting point.In step 75, a check is made as to whether or not there are additionalreference points for the street mapping aside from the three referencepoints already determined. If this is the case, as in the example, thenew starting point is stored again temporarily in step 66 via a programloop 76 and the described process in steps 66-75 is repeated until nofurther reference point of the street is found in step 75. In step 77,the first starting point, the last end point and the intermediatestarting and end points are given out as reference points for a streetmapping which is now smoothed, and a jumping back to the main programaccording to FIG. 1 is affected in step 78.

In the example according to FIG. 16, no further reference point whichwould enable a reduction of the reference point number by means of thesmoothing process according to FIG. 17 could be found within a limit of10 m. This is primarily because the actual course of the street 23 issharply angled. In other street configurations, however, some referencepoints can be economized by means of this smoothing process.

On one hand, proceeding from the heterogeneous collection of data,sufficient relevant data for the mapping of the streets are determinedwith the described process sections for a street system mapping and arestored in a data storage for purposes of navigation, so that adestination indicated by means of street and house number can be foundby a vehicle with compound navigation. On the other hand, the dataremoved from the heterogeneous collection of data are selected by meansof the described process sections via averaging and focal pointformation, linearization and smoothing in such a way that existingcollections of data can accordingly be referred to while taking intoaccount data protection regulations.

The motor vehicle navigation system known from WO 86/07142 is notsuitable for the use of stored street system mapping which has beenobtained from a heterogeneous collection of data according to thepreviously described process. It must be expanded and modified in such away that the storage of the starting point and the destination points ofa distance to be traveled can be carried out by means of inputting thestreet and house number corresponding to these points.

An input routine is needed which can be called up as an alternative tothe known inputting of distance and angle relative to the destinationpoint. It is the object of this routine to determine suitable data fornavigation from the input values for the street and house number of thestarting and destination points. This is affected with the aid ofreduced city map data in the form of street reference points which mustbe available to the system as a data base in a data storage such as aROM, diskette, CD disk, cassette or the like.

In order to keep the storage requirement for the city map data withinacceptable limits, the clear text input of the street name is dispensedwith. Rather, the streets are identified by means of an identificationnumber allotted to them which can be taken from a list. Such a list isincluded as software with the navigation system of the vehicle. Theidentification numbers allotted to the streets can be taken directly outof the data of surveying offices. On the other hand, if the list ofstreet names with the identification numbers is stored in a data storageof the navigation system together with the street system mapping, thestreet name can be called by means of clear text input when inputtingthe starting and destinations points. The corresponding identificationnumber is then determined by the navigation system from the stored listor data.

FIG. 18 shows the navigation system for a motor vehicle in whichstarting and destination points can be inputted for destination-findingnavigation. It comprises an input and output unit 80, a microprocessor81 with a data storage 82, as well as a distance transmitter 83 and adriving direction transmitter 84. The microprocessor 81 processes thedata coming from the distance transmitter 83, direction transmitter 84and operating keys of the input and output unit 10 and further controlsthe output of data and direction arrows on a liquid crystal display 85of the unit 10. The navigation system is operated with five operatingkeys. Numerical values can be changed so as to be larger or smaller onthe LCD 85 with a rocker key 86. The actual numerical value indicated onthe LCD 85 which appears in the lower area of the LCD 85, e.g. on afour-digit seven-segment display 88, is stored by actuating anacknowledgement key 87. The switching of the navigation system within anoffered menu according to lettering 90 on the left-hand side of the edgearea of the unit 80 is affected with a function selection key 89,wherein the information displayed on the LCD 85 is highlighted by meansof an arrow 91 of the LCD 85 at the level of the lettering 90. Anadditional key switch 92 serves to switch the navigation system on andoff. A two-digit seven-segment display 93 in the upper LCD area servesto designate 99 different allowed destinations or intermediatedestinations. A rosette shape 94 of the LCD 85 with 16 differentinvisible arrow elements serves for the directional information, whereinthe controlled directional arrow 95 shows either the northern directionor the direction of the destination to be approached. Instead of therocker key 86, a keyboard can also be used for the numerical input.

The input of the starting and destination points will now be explainedin more detail with the aid of the flow chart according to FIGS. 19 and20. The INPUT menu is selected via the selecting switch 89 afterswitching on the navigation system by means of the key switch 92; in theINPUT menu the selecting key 89 is pressed until the indicator 91 at theleft-hand edge of the display points to "INPUT". The usual input ofdistance and angle relative to the north known from WO 86-07142 iscalled between starting and destination point by means of brieflypressing the acknowledgement key 87. In order to arrive at the inputroutine for street and house numbers, the acknowledgement key 87 must bepressed for approximately 2 seconds until the intermediate destinationnumber 93 begins to blink on the LCD 85. The desired input mode is nowselected. The intermediate destination number to be programmed can nowbe changed with the rocker 86. When the desired intermediate destinationis indicated, the programming can be begun by pressing theacknowledgement key 87. The input can be interrupted at any time bymeans of pressing the selecting key 89; the "NAVIGATION" menu thenappears.

According to FIG. 19, it is determined in step 97 after the start 96 ofthe input routine whether or not the programming has commenced anew oris being carried out for the first time. In the latter case, the systemfirst requires the inputting of a starting point in step 98. In contrastto the programming with the use of distance and angle relative to thedestination, the inputting of a starting point is necessary in order tomaintain a reference point for the coordinates, proceeding from whichthe system can convert the right-angle coordinates from the data intopolar coordinates. When the acknowledgment key 87 is pressed, the text"street" appears on the display 88, with which the system requests theinput of the street number. The acknowledgment key 87 must now bepressed again in order to enter the street number. The navigation systemnow gives the lowest street number contained in the data from the datastorage 82 with the street system mapping. The desired street number canbe set with the rocker 86. When this occurs, the process must beterminated by means of pressing the acknowledgment key 87. The housenumber is entered in the same manner. The lowest house number in thecalled street is first set and can be changed with the rocker 86. Thesystem allows only house numbers which lie between the lowest and thehighest stored house number of the called street, so that it is possiblein every instance to interpolate the coordinates from the data of thestored reference points with the house numbers assigned to them.

When the correct house number is set, this must be confirmed by means ofpressing the acknowledgement key 87. This is followed by a conversion ofthe entered data of the starting point into the coordinates of thestarting point in step 99 with a subprogram according to FIG. 20, whichis explained in the following. After the start is entered, thenavigation system requires that the destination point be entered in step100. This proceeds in exactly the same way as the inputting of thestart, and the coordinates of the destination point are determined andstored with the subprogram according to FIG. 20 in step 101. In step102, a check is then made as to whether or not additional destinationpoints are to be entered for additional intermediate destinations. Theinputting can be terminated in step 103 by means of pressing theselecting key 89. Additional destination inputs can be begun by means ofpressing the acknowledgement key 87.

FIG. 20 shows the flow chart for determining the coordinates of theentered starting and destination points. After the start 104 of thesubprogram, the data of the street system mapping stored in the datastorage 82 is searched in step 105 with respect to the entered streetidentification character or possibly according to the entered streetname. In step 106, it is determined whether or not the street was found.If not, this is indicated in step 107 via the LCD 85 and the input isinterrupted. It can be repeated according to FIG. 19. If the street wasfound, the lowest house number of the stored reference points of thisstreet is called from the data in step 108 and compared in step 109 withthe entered house number. If the house numbers agree, the coordinates ofthe found reference point are taken over as starting and destinationcoordinates, respectively, in an overwritable part in the data storage82 of the navigation system. A new input is requested in step 111. Ifthe house numbers do not agree, additional house numbers are sought instep 112. If no further reference point house numbers are found, this isindicated on the LCD 85 in step 113 and the input is interrupted in step114. It can be repeated according to FIG. 19. However, if additionalhouse numbers were found, the next highest house number is called instep 115 and compared with the entered house number in step 116. If thelatter is still not greater than the entered house number, the programjumps back to step 109 via a loop 117 and checks whether there is nowagreement or whether there are still additional house numbers in thedata.

This process is repeated until the house number called in step 115agrees with the entered house number or is greater than the latter. Inthe latter case, the entered starting or destination point lies betweenthe two reference points of the street called last. The coordinates ofthe starting and destination point must now be determined in step 118 bymeans of linear interpolation between the coordinates of the two lastcalled and temporarily stored reference points corresponding to thedifference between their house numbers. The coordinates determined inthis way are assigned to the house number of the starting or destinationpoint in step 119 and taken over in the overwritable part of the datastorage 82 for navigation. The jumping back into the flow chartaccording to FIG. 19 is now affected in step 120.

This subprogram is to be run through in the same manner for entering thestarting point as well as for entering one or more destination points.It is unimportant whether a house number on a street or square isentered as starting or destination point.

After the starting and destination points are entered, the navigationsystem determines a destination vector with the aid of the coordinatesof the entered starting and destination points taken from the datastorage or determined by means of interpolation by means of subtractingthe coordinates of the starting and destination points. This destinationvector is indicated on the LCD 85 in polar coordinates, wherein thedirectional arrow 95 shows the direction to the destination point andthe display 88 indicates the direct distance between the starting anddestination points. During the navigation driving, the respectivelocation of the vehicle is determined with the aid of the known compoundnavigation and the destination vector is determined for a destinationfinding navigation in a known manner proceeding from the respectivelocation of the vehicle and is displayed.

While the invention has been illustrated and described as embodied in amethod of inputting and starting and destination points into anavigation system, it is not intended to be limited to the detailsshown, since various modifications and structural changes may be madewithout departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims.
 1. A method of inputting starting anddestination points into an electronic navigation system of vehiclecomprising the steps of:storing relevant data of street system maps in adata storage, which data contain a street identification character andcoordinates of reference points of streets, with as assigned housenumber; entering the street identification character and the housenumber of one starting and destination points one after the other eachtime one of said starting and destination points is inputted into thenavigation system; searching the data storage according to the enteredstreet identification characters; comparing each said house number ofreference points of a street found in the data storage during thesearching with the inputted house number, transferring coordinates ofthe house number associated with one of said reference points into astorage of the navigation system when the inputted house number agreeswith the house number associated with said one of said reference points;storing data of the reference points temporarily with house numbersadjacent to the inputted house number when the inputted house numberdiverges from the house numbers of the reference points present in thedata storage; and determining coordinates of the inputted one of saidstarting and destination points by interpolating coordinates of thereference points with the adjacent house numbers and transferring thecoordination of the inputted one of said starting points into thestorage of the navigation system.
 2. A method according to claim 1,wherein the street identification character consists of a number whichis stored in a data file of the data storage containing the street listof the street system maps.
 3. A method according to claim 1, furthercomprising the step of determining a destination vector from thecoordinates of said starting and destination points determined by anavigation computer, and indicating the destination vector by thenavigation system.
 4. A method according to claim 3, comprising the stepof converting the determined destination vector into polar coordinatesand indicating it on a destination display and a distance-to-destinationdisplay.